[jortiz]

Note: I have answers for the first two questions, I'm more so asking about how to find the volume assuming its in a non-ideal situation. Ive tried using Van der Waal's equation, but have had no luck trying to solve for volume. Every thing I look up  for Van der Waals is to solve for pressure, and not volume. When I tried to rearrange the equation, I just ended up with a mess of numbers that didn't make sense and have tried this problem with many other chem students only to be stuck with the same problem. Any help would be greatly appreciated, and I hope that i obeyed the rules of the board with this post.


A cylinder fitted with a moveable piston is subject to a constant external pressure of 1.00 atm.
Assume that the weight of the piston is negligible and that there is no friction between the piston
and the walls of the cylinder.
Initially, the cylinder contains 300.0 mL of nitrogen gas and 900.0 mL of acetone vapor at
80.0°C. The cylinder is cooled so that the contents reach a temperature of 25.0°C. During the
cooling process, the acetone changes from a gas to a liquid. The density of acetone at 25.0°C is
0.7925 g/mL. For nitrogen, a = 1.390 atm·L2/mol2 and b = 0.03913 L/mol. For acetone,
a = 14.09 atm·L2/mol2 and b = 0.0994 L/mol.

1. Assuming that all gases behave ideally, calculate the volume of the cylinder at 25.0°C.
2. Again assuming gases behave ideally, calculate the work for the cylinder during this process.
3. Now assume that the gases do not behave ideally. Calculate the volume of the cylinder at
25.0°C.

[Borek]

Show how you started and where did you hit the wall.

[jortiz]

Well i suppose my question is whether or not you can use van der waals to solve for volume because if so I have no idea how to. Even in my chem book it says use van der waals to solve for pressure. Ive googled this and I found a link to a site that gives an example of using calculus to solve for the problem, but I'm not sure thats what my instructor is looking for.

For the first problem, I added the two volumes, and I assumed the pressure and moles were constant so I used V₁/T₁=V₂/T₂ and just solved to find the second volume. The volume was smaller so it made sense.

The second problem, I used work=-P X change in volume. I got a positive number which makes sense because the system is losing heat.

The third question, Ive tried plugging numbers in and making assumptions, using density of acetone to come up with grams and convert to moles but i dont really get anywhere with it